Your eyes are complex organs with many parts that must work together to produce clear vision. Read on to get a basic overview of eye anatomy and learn about common eye conditions.

The major parts of your eye are listed below. Problems or malfunctions in various parts of your eye can cause many common eye conditions.


The cornea is a part of your eye that helps focus light.

Tear ducts

The openings to the tear ducts are located in your upper and lower eyelids at the inner corner of each eye. Tears are mainly produced by the lacrimal gland and spread from your outer, upper eyelid over the surface of your eye. Tears keep your cornea lubricated and clear of debris. The tear ducts drain the tears away.

Iris and pupil

The colored part of your eye is the iris. It’s a structure that contains muscles that control the pupil, which is the opening in the middle of your eye. The iris controls the amount of light coming in through the pupil.

Lens and retina

The lens is behind the pupil. It focuses light onto the retina, the light-sensitive cells on the back of your eyeball. The retina converts images into electrical signals that are sent to your optic nerve.

Optic nerve

The optic nerve is a thick bundle of nerve fibers attached to the back of your eye. It transmits visual information from the retina to your brain.

When your eyes don’t focus light properly, you’ll experience blurry vision. Types of refractive errors include:

  • myopia (nearsightedness), which is when faraway objects look blurry
  • hyperopia (farsightedness), which is when close-up objects look blurry
  • astigmatism, which can result in blurry vision because your cornea is not perfectly shaped to direct light into your eye
  • presbyopia, which is farsightedness that’s caused by the loss of elasticity of your eye’s lens due to aging

Glasses, contacts, or surgery can usually correct these issues.

Glaucoma is increased pressure of the fluid inside your eye. This can cause optic nerve damage. Glaucoma is a common cause of blindness.

According to the National Eye Institute, your glaucoma risk is higher if you:

  • are over 40 years old
  • are Hispanic, Latino, or African American
  • have a family history of the condition

A cataract is a clouding of the lens, which causes blurry or color-tinted vision. People with cataracts often report seeing “halos” surrounding objects they’re looking at, particularly at night. This condition is most common in older adults.

Cataracts can be treated with surgery that replaces the damaged lens with an artificial lens.

AMD is gradual damage to the cells of the macula, which is part of the retina. This condition is most common in people ages 55 years and older.

AMD causes blurry vision, especially in the center of the field of view. According to the Centers for Disease Control and Prevention (CDC), AMD is the most prevalent cause of blindness and vision loss in people ages 65 years and older in the United States.

Amblyopia is commonly referred to as a “lazy eye.” It occurs when vision has not properly developed in the eyes, and the brain begins to favor the eye with better vision.

This happens if one of the eyes is blocked from producing clear images during the critical years from birth to 6 years old. One eye may be affected by problems such as lid droop, a tumor, or misalignment (strabismus) that are not corrected when a child is young.

If a young child has vision problems or if their eyes do not align, it’s crucial for an eye doctor to evaluate them to ensure that the condition is properly diagnosed and treated.

Diabetic retinopathy is damage to the blood vessels of the retina due to diabetes. It causes blurred or dark spots in the field of vision and can eventually lead to blindness.

The best way to avoid this condition is to manage your blood sugar and see your eye doctor every year for a dilated eye exam. Proper care can reduce complications.

When the retina separates from the back of your eye, it’s called a detached retina. This causes blurry vision and partial or complete loss of vision and should be treated as a medical emergency.

Dry eye is a lack of tears. It’s usually due to a problem with the tear ducts, the eyelids, or tear formation (such as low production or too-rapid evaporation). It can also be a side effect of certain medications. This condition can cause pain and blurry vision.

Your eyes are complex, and it’s important to know the different parts and how they function.

Knowing how each part works can help you recognize vision problems and symptoms of common eye conditions so you can get treatment early and maintain your eye health.